Hardin Marine

O2 Spacer, Stock Mercury Riser

This Unique 1" thick adapter plate provides an installation option for retro fitting a Oxygen sensor and or air fuel ratio gauge for tuning purposes Into Mercruisers most common Wet Joint style exhaust manifold systems. The part is CNC machined from 6061 Billet Aluminum then Naval Spec Hard Coat anodized for corrosion resistance (Beware of inferior non-coated versions)

A unique feature of this adapter is the cooling parts that run along each side of the sensor maintaining consistent temperature of the spacer. Designed to accept all popular 18MM O2 Oxygen sensors.

• Mercury 3 and 4" Riser Gasket(700-32080) 2 Required
• Stainless Steel 18MM Oxygen Sensor Plug(620-50031) 1 Required

TECH NOTE: Will O2 Sensors Work In marine exhaust systems?

YES FOR TUNING but they have limitations as water / moisture is a byproduct of combustion. Often boaters find there is moisture in their exhaust system that have collected or made their way inside of what is better known as the "DRY" exhaust stream of their exhaust system. Anything from steam like to little water droplets about 1/32" all around the inside of the exhaust. This is because water IS a by product of combustion. same thing you see on a cold morning behind cars. sometimes you see water dripping out.

Don't take our word for it ask a real rocket scientist: https://www.grc.nasa.gov/www/k-12/airplane/combst1.html

This is why O2 Sensors are great for tuning but have a limited long term life span unless protected by Catalytic converters like on New Marine engine offerings. So you know gas is known as a hydrocarbon based fuel. And we all know what hydro means WATER.

Oil Cooler - 2" Diameter, 16" Overall Length, 1" NPT Connection

Featuring thirty-one 1/4" cooling tubes with displacement baffles! Large 1" NPT oil connections for increased flow with an 1/8" NPT drain. Rated operating pressure up to 150 PSI. Recommended for engines up to 425 horsepower.

Oil Cooler - 2" Diameter, 16" Overall Length, 1-1/4" Hose Connection

Featuring thirty-one 1/4" cooling tubes with displacement baffles! Large 3/4" NPT oil connections for increased flow with an 1/8" NPT drain. Rated operating pressure up to 150 PSI. Recommended for engines up to 425 horsepower.

Oil Cooler - 2" Diameter, 16" Overall Length, 1-1/4" Hose Connection

Featuring thirty-one 1/4" cooling tubes with displacement baffles! Uses 1/2" inverted flare oil connections typical to Mercury OEM coolers and an 1/8" NPT drain. Rated operating pressure up to 150 PSI. Recommended for engines up to 425 horsepower.

Oil Cooler - 2" Diameter, 16 Overall Length, 3/4" NPT Connection for Water and Oil

Featuring thirty-one 1/4" cooling tubes with displacement baffles! Large 3/4" NPT water and oil connections for increased flow with an 1/8" NPT drain. Rated operating pressure up to 150 PSI. Recommended for engines up to 425 horsepower.

Oil Cooler Cover Gasket - Port Side

These gaskets are used with Mercury Racing flywheel housing oil coolers.

Oil Cooler Cover Gasket - Starboard Side

These gaskets are used with Mercury Racing flywheel housing oil coolers.

Oil Cooler Jam Nut

Oil Cooler - 2" Diameter, 8" Length, 1" NPT Connection

This cooler features thirty-one 1/4" cooling tubes with displacement baffles. It also has 3/8" NPT oil connections with an 1/8" NPT drain. Operating pressure of up to 150 PSI. Designed for power steering or transmission applications.

Oil Cooler - 2" Diameter, 8" Length, 3/4" NPT Connection

This cooler features thirty-one 1/4" cooling tubes with displacement baffles.  It also has 3/8" NPT oil connections with an 1/8" NPT drain.  Operating pressure of up to 150 PSI.  Designed for powersteering or transmission applications.

Oil Cooler - 2" Diameter, 9" Overall Length, 1-1/4" Hose Connection

• 3/8" NPT oil connections
• 1/8" NPT drain
• Operating pressure of up to 150 PSI.
• Replaces Mr Cool MRC205EE-05, Seakamp 25134, R&D Enterprises RD205EE-05, Sen-Dure 1125-12-S

Oil Drain Hose Fitting

This fitting is a replacement for 620-242179

Oil Drain Hose Fitting

This fitting is a replacement for 620-242180

Oil Filler Plug

These oil resistant rubber oil fill plugs are used to seal oil fill holes in valve covers.  This cap measures 1.22 in diameter.

• Oil Line Thru Hull for Mayfair Trim Tabs (4) required per kit.
• 4-1/2" long.
• Also replaces Mercury OEM #844142A01 and #845521A1
• Sold Each

Oil Pressure Sender 0-80 PSI, Hardin Gauge (2018 and Earlier), Medallion

Oil Pump Drive Mandrel Kit - External Oil Pump Drive Mandrel

For use on supercharged engines to space the oil pump drive gear out away to clear the supercharger pulley.  This billet 6061-T6 aluminum drive mandrel with stainless mounting hardware is the very best we've seen anywhere.  Designed to be used in conjunction with a 755-3100 reverse mount crossover mounted alternator and a 755-2000 pulley and 625-3129 spacer.  Each mandrel features stainless belt guides and mounts to any 6 bolt pattern crank pulley and will accept standard 1" ID X 1" Wide with 1/8" keyway oil pump drive gears.

Oil Pump Drive Mandrel Kit - External Oil Pump Non-Supercharged Drive Mandrel

For use on supercharged engines to space the oil pump drive gear out away to clear the supercharger pulley.  This billet 6061-T6 aluminum drive mandrel with stainless mounting hardware is the very best we've seen anywhere.  Designed to be used in conjunction with a 755-3100 reverse mount crossover mounted alternator and a 755-2000 pulley and 625-3129 spacer.  Each mandrel features stainless belt guides and mounts to any 6 bolt pattern crank pulley and will accept standard 1" ID X 1" Wide with 1/8" keyway oil pump drive gears.

• Non-corrosive hardware
• Gasket sealed lens and bezel to prevent fogging
• Plastic body Domelux Technology Lens
• White back light
• Senders sold separately
• 2 1/16 hole size, Outer diameter 2 5/16
• Not Designed to be used with Diesel Engines.
• NOTE: This older style gauge matches 2018 and earlier model Hardin Gauges.

Need help measuring your gauges so you know what to look for when you finally upgrade to a more polished set? Check out this handy tutorial!

Oldsmobile 455 2-piece Rear Main Seal- Sold Each

These excellent rear main seals are designed to replace worn, deteriorated original equipment seals and provide years of trouble free service

Sold Each

Olds 350-455 10 Quart Stern Drive / Jet Drive Performance Oil Pan

Marine oil pans are subject to special conditions. Closed engine compartments create a lack of air flowing around the oil pan causing higher oil temperatures, which can destroy the lubricating properties of the oil in low capacity pans. The motion of the boat in the water sloshes the oil in pans that don't have correct baffling. Air is ingested through the oil pick-up resulting in momentary loss of oil pressure. The oil is tossed into the crank, which foams and aerates it. The pounding effect of oil in the pan cause fractures in pans without reinforcement.

• 1/2"-20 drain plug

The design and construction of Dooley oil pans insures there are no problems, even in the roughest conditions. Here are just a few of the Dooley oil pan features:

• High capacity oil sumps
• 16 gauge steel construction
• Precision oil baffles
• Block fitted and double leak checked for a perfect fit every time
• Gold iridite plated for corrosion protection
• Tig welded for maximum strength
• Oil temperature gauge bung provisions
• One way oil control doors ensure oil is contained at the oil pump pick-up where it needs to be.
• Uses existing engine mounted windage tray

These oil pans offer a value unsurpassed in the marine industry today.

Olds 350-455 Xtreme Marine Seal™ Valve Cover Gasket- Sold in Pairs

There is nothing more frustrating than a leaking valve cover seal, so don't settle for anything less than the best. That's why professional engine builders nationwide demand Xtreme Marine Seal valve cover gaskets. Produced from a blend of polymer and cork to provide a gasket that will last.

Sold in Pairs

Big Block Olds 455 Intake Manifold Stainless Steel Allen Bolt Kit

We offer a full selection of intake manifold bolt kits to fit most popularmarine engines. These kits come complete with the correct number of bolts andstainless steel washers. Don't install your new intake manifold with anythingless.

Stainless Steel Bolt Kits - Olds Valve Cover Bolt Kit
We offer a full selection of manifold bolt kits to fit most popular marine engines.  These kits come complete with the correct number of bolts

Stainless Steel Bolt Kits - Olds Header Bolt Kit
We offer a full selection of manifold bolt kits to fit most popular marine engines.  These kits come complete with the correct number of bolts and